Insulating screw-shell.



PATENTED APR. 10, 1906.

2 SHEBTS-SHEBT 1.

H. HUBBELL.

INVENTOR INSULATING SCREW SHELL.

APPLICATION FILED JUNE 28,1905.

S E S S E N .H W

UORNEY No. 817,484. PATENTED APR. 10, 1906.

H. HUBBELL. INSULATING SCREW SHELL.

APPLICATION FILED JUNE 28, 1905.

2 SHEETS-SHEET 2.

www a@ WITNESSES INVENTOR L BY 'MTORNEY UNITED STATES PATENT OFFICE.

i Speccation of Letters Patent.

v Patented April 1906.

Application filed June 28,1905. ySerial No. 267,357.

`sulating Screw-Shell, of Iwhich the following is a specification.

This invention has for its obj ect to provide a simple and inexpensive insulating screwshell ada ted for general use, and especially adapted or use as a socket-shell Jfor incandescent electric lamps ofthe Edison type and as an adapter to adapt Thomson-Houston sockets to receive Edison lamps. This structure has been devised to meet the re uirements of the trade `and for the reason t at it is chea er and very muchibetter in every way to have the insulating-lining, which is an essential feature of construction, an integral part of the screw-shell rather than oi' the socket, the requirements being that the insulating screw-shell be so constructed as to permit of its being quickly and conveniently attached to either an Edison or a Thomson- Houston socket, that when attached it be firmly securedin lace, so that there will be no danger ofits etachment in removing a lamp, and at the same time that it be adapted for convenient removal especially when used for an adapter for Thomson-Houston sockets, leaving the socketsagain in condition to receive Thomson-Houston lamps.

`With these andother objects in view I have devised the simple and novel insulating screw-shell of which the following description, in connection with the accompanying drawings, is a specification, reference characters being used to indicate the several parts.

shell is formed when the mica Figure 1 is an elevation, partly broken away, showing the use of my novel insulating screw-shell in connection with an Edison socket. F ig. 2 is a plan view, on an enlarged scale, of the screw-shell detached. Fig. 3 is an inverted plan view corres onding therewith. Fig. 4 is a longitudina section showing the manner in which the up er end ofthe isk is self-retaining in place. Fi p5 is Ian elevation, partl broken away, s owing the use of my nove insulating-shell as an adapter of an "Edison lamp to a Thomson-Houston socket.

' Figs.` 6 and 7 are longitudinal sections corresponding with Fig. 4, showing variant modes of retaining` the mica disk in place; and Fig. 8 is a sectional view showing my novel insulating screw shell as applied to a Thomson- Houston socket ready to receive an Edison lamp.

A denotes'an Edison socket, B a Thomson-Houston socket, and C my novel insulatingscrew-shell as a whole. 10 denotes the screw-shell, which is made of metal and is provided with an inwardly-turned contactange 11, which is provided with a screw-hole 12 to adapt it Jfor use in an Edison socket, as will be more clearly eX lained, and a central opening 29, of greater iarneter than the center screw, so t at no current can pass from either form of center screw to screw-shell 10. 13 denotes an` external insulating-sleeve, which lits the shell closely. Prongs 14 may be struck out from the shell to en age the insulating sleeve and make its etachinent Jfrom the shell 4impossible under the ordinary conditions of use.

15 denotes a relatively thin insulating--A disk, preferably of mica, which lies in the base oi the screw-shell and is provided with a central opening 16, through which the center screw passes freely. This disk may be made large enough to fit closely and be self-retaining in the screw-shell, asin Fi 4, or it may be retained in place by inward y-turned lugs 17, struck out from the metal of the screwshell and turned inward, as in Fig. 6, or a groove 18 may be provided to receive it and retain it in place, as in Fig. 7.

When my novel insulating screw-shell is used in connection with an Edison socket, as in Fig. 1, a screw 19 is passedthrough hole 12 in the contact-flange and into engagement with the usual term1nal20 within the socket. In addition to screw 19 the insulating screw- `shell is held in place by a center screw 21,

without mv novel insulating screw-shell..

The screw-shell of the lamp is turned into the insulatinor screw-shell until the center contact 24 ci the lamp engages the center screw 21 ofthe insulating screw-shell. The current passes through center screw 21 and center contact w24 to the carbon lament ofthe lamp, thence to the screw-shell 23 of' the lamp,

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screw-shell 10 of the insulating screw-shell, and through screw 19 to terminal 20 of the socket, insulating-sleeve 13 acting to insulate screw-shell 10 from the neck of the socket, which is unlined and is indicated by 25.

When my novel insulating screw-shell is used in connection with a Thomson-Houston socket, as inFig. 5, the insulating screw-shell is locked in the socket within the neck there'- of, which is unlined and is indicated by 26, by means of a nut 27, which engages the center screw 28 of the socket, a washer 22 being interposed between. the nut and the insulatingdis The contact-flange of the insulating screw-shell lies closely 1n engagement with the contact-ring 3() of the socket. The current passes through center screw 28 ,and the center contact of an Edison lamp, as before, to the carbon filament, thence to the screw-shell 23 of the lamp, screw-shell 10 `of the insulating screw-shell, and thence throu h the contact-ilange to the contact-ring of the socket. I

By interposing a washer 22 between the nut and the insulating-disk the connection of the adapter to the socket is made perfectly safe and secure, as in the other form, and it is made practically impossible to turn the insulating screw-shell out of the socket with the lamp in removing the lamp. Should the lamp-base stick in the insulating screw-shell tightly enough to cause the latter to turn, the Washer will turn with it slightly, but without startin the nut, rotation of the washer acting to ook the washer tightly to the nut, so

that it is made practically impossible for the insulating screw-shell to be turned out without rst turning off the nut.

Having thus described my invention, I claim- 1. An insulating screw-shell of the character described, comprising a screw-shell which receives an externally-threaded lamp-base, an insulating-disk having an opening to receive the center screwof an internallythreaded lamp-socket, a washer to engage the disk, a nut which enga es the center screw and bears upon the was er and an external insulating-sleeve secured to the screw-shell. l

2. The combination with a socket-shell having an unlined neck, of an. insulating screw-shell comprising a screw-shell which receives an externally-threaded lamp-base and is provided with a contact-flange, an insulating-disk lying in contact with the lange and having an opening for a center screw,-an external insulating sleeve secured to the screw-shell, a washer lying in contact with, the insulating-disk and a nut engaging a center screw to retain the insulating screw-shell in place, said contact-ange having a central opening of greater diameter than said center screw.

In testimony whereof l affix my signature in presence of twowitnesses.

HARVEY HUBBELL.

Witnesses:

A. M. WoosTER, S. W. ATHERTON. 

